United lost away at Newcastle, thanks to Matt Ritchie's second half winner, to condemn the Red Devils to back-to-back away defeats - following Tottenham's 2-0 victory at Wembley - leaving Liverpool breathing down their necks in the battle for second place.

Romelu Lukaku's early season golden touch has faded somewhat with two goals in his previous eight Premier League appearances, with Alexis Sanchez still bedding in after his switch from Arsenal.

Paul Pogba has lost his mojo as well, with early withdrawals against Spurs and the Magpies and a place on the bench against Huddersfield.

Manchester United are lost two of their last three matches (Image: AFP/Getty)

Suddenly there is an identity crisis at United. The 4-2-3-1 formation has become problematic, Chris Smalling still struggles to pass, Pogba is out of form, Nemanja Matic is struggling and Anthony Martial is playing on the right.

United's shoddy shape is particularly troubling as they prepare for their most pivotal period of the campaign. Huddersfield in the FA Cup fifth round on Saturday precedes Sevilla away in the Champions League on Wednesday week before the February 25 visit of Chelsea in the Premier League.

Chelsea have beaten United three times in the last four but the one failure remains the outstanding performance by Mourinho's side. He benched the in-form Zlatan Ibrahimovic and Henrikh Mkhitaryan, switched to 3-5-2 with Jesse Lingard up front and schooled Antonio Conte. United won 2-0 in what remains the Old Trafford highlight of Mourinho's reign.

Mourinho's tailored formations are his tactical calling card and he did it again at Arsenal in December, where United were dangerous at both ends in that captivating 3-1 triumph. Mourinho has not used a back three since and United have conceded three in their last nine.

The United manager may have considered a defensive tweak had Eric Bailly not suffered an ankle injury. Victor Lindelof has struggled to regain the trust of a manager who was prepared to pay £30.9million for him and Marcos Rojo was such a grave danger to his own side he collected five yellow cards in his first five domestic games.

Does Paul Pogba need to play in a three-man midfield? (Image: Getty Images Europe)

Ander Herrera and Marcus Rashford have succumbed to muscle injuries but Mourinho does not expect their lay-offs to be long-term and Bailly and Zlatan Ibrahimovic could return for the Sevilla away leg next week. Daley Blind has a 'small problem' and Marouane Fellaini could return at the end of next month.

The FA Cup and Champions League represent United's only chances of silverware this term and the upcoming ties intensify the need for Mourinho to settle on a more fluid formation. The best players do not always make for the best team and switching to 4-3-3 could withdraw Jesse Lingard or Anthony Martial from the XI.

Samuel Luckhurst

City have proved that in an era where managers are choosing different teamsheets for different occasions the best way to assemble a fluid side is to have a settled XI. United have arguably seven untouchables (when fit) in David de Gea, Bailly, Antonio Valencia, Matic, Pogba, Alexis Sanchez and Romelu Lukaku. How Mourinho complements them between now and May could be the difference between a successful and unsuccessful season.

Luke Shaw has the pace and adventure to develop into a fine wing-back or winger. Ander Herrera's form has plummeted this term but, as mentioned earlier, the best players do not always make for the best team. Anthony Martial and Jesse Lingard would be aggrieved but Herrera could be the ideal supplement for Matic and Pogba against the elite.

Sanchez is such a live wire he would be wasted on the wing and deserves a free role behind Lukaku.

Ciaran Kelly

Personnel wise, there were few complaints when the team sheets dropped in at St James' Park at around 1.17pm on Sunday.

Clearly, Jose Mourinho has made up his mind when it comes to his strongest line-up after fielding the same team for tough trips to the north-east and Wembley 11 days previously.

And, yet, both times, United were well short. Worryingly, too, there were few options on the bench to change the game when they went behind in both matches.

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But this season is far from lost, in the cups at least, as we enter the business end of the campaign and there are a couple of things that could shake things up once Eric Bailly returns from injury.

Alexis Sanchez struck up a fearsome relationship with Antonio Di Natale while playing as a No.10 at Udinese and that role would give him even more freedom to do all that roaming he loves.

Ideally, it would be great to bring a defensive midfielder into the fold to give Paul Pogba the platform to really shine but that will have to wait until the summer when a consistent option becomes available.

Charlotte Duncker

If there's any real debate to be had over United's best XI the hardest decisions don't come at the back. Performances so far this season have shown if Mourinho fielded a back four there's not much debate to be had over the four best players to fit those positions.

Valencia is arguably United's only right back option while Shaw's shown in recent weeks why he should be given a solid run to make the left back position his own before the end of the season. United have missed Bailly while he's been out injured and Jones is a far more solid option to accompany him at in the middle.

Recent performances show Mourinho needs to ditch the two man midfield and the way to get the best out of Pogba is to play in a 4-3-3.

Matic is the obvious answer to play alongside Pogba but the third option is a less than obvious pick. This is where Mourinho needs to strengthen most in the summer but for now Herrera, despite a less than inspiring season, would have to go in that midfield three.

United's attacking line poses the biggest problem with Sanchez and Martial both wanting that left hand role. But, Martial's shown he shouldn't be playing down the right and Sanchez's versatility means he should start on the right with the option to float inside behind Lukaku.

Conor Mummery

This is Mourinho's very best option. It fits in all his best players and uses them all in their best way.

Martial and Sanchez offer goal scoring threats from both flanks and offer a fluidness to United's attacks.

Pogba quite simply has to have two other midfielders playing alongside him to allow him to stroll around the pitch and affect both going forward and in defence.

Luke Shaw is starting to show why he was once the most expensive teenager in football and has earned the trust Mourinho is now showing in him - he offers slightly more than Ashley Young at this point.

Thomas Bristow

The back four picks itself at this stage, with Jones and Smalling prone to errors together, the latter has already proven himself in a defensive line with Bailly.

Pogba needs to train himself to sit on a leash in midfield rather than forcing Mourinho to sacrifice an all-important forward to give him safety in midfield - for £90million it is the least you expect.

The pace, and threat, of Marcus Rashford and Martial on either wing to go with the trickiness and guile of Sanchez and the goal-scoring ability of Lukaku and the side has a nice attacking balance.